Isolation and characterization of a novel silicate-solubilizing bacterial strainBurkholderia eburneaCS4-2 that promotes growth of japonica rice (Oryza sativaL. cv. Dongjin)

Abstract

The current study aimed to isolate and identify japonica rice (Oryza sativa L. cv. Dongjin) root-associated rhizobacteria and to investigate their ability to solubilize silicate, produce indole acetic acid (IAA), promote plant growth, and encourage silicon (Si) uptake and deposit in plants. A single bacterial isolate was selected on the basis of its silica-solubilizing ability and IAA production. The 16S rRNA gene sequence of the isolate identified it as Burkholderia eburnea CS4-2. Burkholderia eburnea CS4-2 produced high amounts of IAA at pH 8. When combined with silica fertilization, soil inoculation with CS4-2 promoted all growth attributes over those of the water-treated (control) and insoluble silica-fertilized plants. Microscopic observations also demonstrated a significant difference in the Si deposits on the leaf epidermis of rice plants under different treatments, indicating that more Si was deposited in plants fertilized with both B. eburnea CS4-2 and insoluble silica than in either insoluble silica-fertilized or water-treated plants. Inductively coupled plasma spectrometry analysis confirmed the same trend of Si concentration in whole-plant biomass of the rice that received the same treatments, respectively. Therefore, we conclude that B. eburnea CS4-2 has the ability to produce IAA under high-pH conditions, solubilize silicate, and promote plant growth.

Isolation and Characterization of the High Silicate and Phosphate Solubilizing Novel Strain Enterobacter ludwigii GAK2 that Promotes Growth in Rice Plants

“…Microorganism mediated phosphate dissolution occurs through the production of various enzymes, such as phosphatase and phytase [11]. However, the acidolysis phenomenon has been reported for the dissolution of silicates [12]. There is evidence of the potential role of phosphate solubilizing bacteria (PSB) in the enhancement of plant growth through P uptake by plants.…”

“…The microorganisms isolated as described above were punched into petri plates with glucose agar medium (10 g L −1 glucose) containing 0.25% insoluble silicate (IS) (Mg 2 O 8 Si 3 ) to detect silicate solubilization and National Botanical Research Institute's Phosphate (NBRIP) medium with 0.25% insoluble phosphate (IP) [Ca 3 (PO 4 ) 2 ] using a wood pick and cultured at 30 • C for 24-168 h [12,14]. The clear zone formed was identified and the diameter was measured.…”

“…The method described by Kang et al [12] was followed to quantify the Si content of the plant. In brief, 0.5 g of the lyophilized crushed powder was soaked in 0.5 M HCl and rinsed through double distilled water before oven drying.…”

Silicon-Solubilizing Media and Its Implication for Characterization of Bacteria to Mitigate Biotic Stress

“…feldspar, muscovite, biotite, and magnesium trisilicate with soluble phosphate sources (di-potassium hydrogen phosphate; K 2 HPO 4 and di-sodium hydrogen phosphate; Na 2 HPO 4 ); and agar based media containing glucose and magnesium trisilicate as sole source of nutrition (Sheng et al, 2008;Kang et al, 2017;Vasanthi et al, 2018). Number of bacterial strains of genus Bacillus, Pseudomonas, Proteus, Rhizobia, Burkholderia, and Enterobacter are known to release silicon from silicates and promote plant growth (Meena et al, 2014a;Wang et al, 2015;Kang et al, 2017;Kumawat et al, 2017;Chandrakala et al, 2019;Lee et al, 2019). However, due to the common mechanism of solubilization (organic acid production) and quantification method (molybdenum blue method) for both phosphate (P, Fiske and Subbarow, 1925) and silicon (Si, Elliott and Synder, 1991) there is unavailability of a concrete siliconsolubilizing media.…”

Effects of background fertilization followed by co-application of two kinds of bacteria on soil nutrient content and rice yield in Northeast China

“…Our study showed that applications of both B. mucilaginosus and A. niger could affect the content of available Si in various organs of the above-ground part of the rice plant (Figure 1). The absorption and accumulation of Si could be promoted, and the distribution of Si in the stems, leaves and spikes could be affected [55] . The content of available Si from high to low is ranked as: leaves, stems, spikes.…”